Along with high integration of LSI, circuit line widths demanded for semiconductor devices are being reduced year after year. To form desired circuit patterns in these semiconductor devices, a highly precise original pattern (also referred to as a reticle or mask) is needed. To produce a highly precise original pattern, electronic beam lithography technology using an electronic beam drawing apparatus is used.
With an electronic beam drawing apparatus, a drawing area is divided into strip-like stripes; by using these stripes as drawing units, an electronic beam is emitted while a stage on which a target such as a mask is placed is moved so that a pattern is drawn on the target. As drawing methods, variable-speed drawing, in which the stage speed is varied depending on the pattern density, and constant-speed drawing, in which the stage is moved at constant speed, are known.
In constant-speed drawing, the stage is accelerated at predetermined acceleration; after the stage speed has reached a target speed, drawing starts. If the drawing pattern is positioned at an end of the target, a run-up start coordinate for drawing this pattern at the target speed may exceed a limit coordinate. That is, there may be a case in which a run-up distance cannot be assured. In this case, a limit error has been avoided by reducing the target speed to shorten a distance needed for run-up.
Similarly, if the stage is decelerated at predetermined acceleration after a pattern has been drawn in one stripe, a stage stop position may exceed a limit coordinate. That is, there may be a case in which a stop distance cannot be assured. In this case as well, a limit error has been avoided by reducing the target speed to shorten the stop distance.
However, if constant drawing is performed at reduced target speed to avoid a limit error, there has been the problem that since drawing is performed by reducing the speed in the entire stripe area, throughput is dropped.